Hydrocarbon-containing compositions

ABSTRACT

A POUR POINT DEPRESSANT FOR CRUDE OIL, SHALE OIL OR A FUEL OIL WHICH COMPRISES 35-100 WT. PERCENT OF RESIDUA FROM THE DISTILLATION OF CRUDE OR SHALE OIL IS DISCOLOSED. THE POUR POINT DEPRESSANT IS A COPOLYMER OF EHTYLENE AND A VINYL OR C1 TO C30 HYDROCARBYL SUBSTITUTED VINYL ESTER OF A C1 TO C30 SATURATED ALIPHATIC MONOCARBOXYLIC ACID, SAID COPOLYMER HAVING A NUMBER AVERAGE MOLECULAR WEIGHT OF ABOUT 4,000 TO 60,000 AND CONTAINING ABOUT 40 TO 95 WT. PERCENT ETHYLENE.

United States Patent 01 :"fice 3,567,639 HYDROCARBON-CONTAININGCOMPOSITIONS Colin Aaron and Alan Harold Edwards, Charlton,

Wantage, England, and Keith Campbell Tessier, Westfield, N.J., assignorsto Esso Research and Engineering Company No Drawing. Filed May 8, 1967,Ser. No. 636,597 Claims priority, application Great Britain, June 1,1966, 24,368/ 66 Int. Cl. Cm 1/28 US. Cl. 252--56 7 Claims ABSTRACT OFTHE DISCLOSURE A pour point depressant for crude oil, shale oil or afuel oil which comprises 35-100 wt. percent of residua from thedistillation of crude or shale oil is disclosed. The pour pointdepressant is a copolymer of ethylene and a vinyl or C to C hydrocarbylsubstituted vinyl ester of a C to C saturated aliphatic monocarboxylicacid, said copolymer having a number average molecular weight of about4,000 to 60,000 and containing about 40 to 95 wt. percent ethylene.

This invention relates to fuel compositions based on residua-containingfuels, and other base oils.

Although various pour point depressants are known and have been used,they have been reasonably successful only with middle distillate fuels.It has been found difficult to obtain a potent pour point depressant forshale oils, residua or residua-containing fuels. We have now discoveredcertain polymers which are potent as pour point depressants in certainhydrocarbons, e.g, residua-containing fuels or crude oils.

According to this invention hydrocarbon-containing compositions comprisea major proportion by weight of a residua-containing fuel, shale oil ora crude oil and a minor proportion by weight of a copolymer of ethyleneand vinyl (or hydrocarbyl substituted vinyl) ester of a carboxylic acid,said copolymer having a number average molecular weight of above 3,000and preferably above 3,500.

The residua-containing fuel is defined as a fuel comprising residua fromthe distillation of crude oil or shale oil or mixtures thereof.Generally the residua-containing fuel (hereinafter referred to simply asthe fuel) will contain from about 35% to 100% by weight of residua, andwill usually have kinematic viscosities ranging from 10 to 3,500 cs. at100 F. However, the viscosity of some particularly waxy fuels may bedifficult to measure accurately at 100 F., and it is well known in theart that the viscosity of such fuels is measured by the viscosity at ahigher temperature. The viscosity at 100 F. is then obtained byextrapolation using a R.E.F.U.T.A.S. viscosity temperature chart. Theextrapolated kinematic viscosity will then fall in the desired range at100 F. The R.E.F.U.T.A.S temperature viscosity chart was designed by C.I. Kelly, M.S.C. Tech., F.I.C., M. Inst., P.T., A.M.I.A.E. Copyrightreserved in Great Britain and U.S.A. by Paird & Tatlock (London) Ltd.,14-17 Cross Street, Hatton Garden, London, E.C.1. Fuels having kinematicviscosities of between 15 and 1500 cs. at 100 F. are preferred, and alsofuels wherein at least 60% by weight of the fuel boils above 500 F. atatmospheric pressure are particularly suitable.

The fuels to which this invention applies include therefore, light,medium, heavy and bunker or furnace fuels, the viscosities ranging fromabout 152000 cs. at 100 F., but usually, however, the maximum viscositywill be about 900 cs. at 100 F. Examples of suitable fuels are describedin PB Industrial and Marine Fuels of BS2689: 1957.

3,567,639 Patented Mar. 2, 1971 Crude oils from which the fuels arederived, or shale oil may also be used.

The preferred ethylene comonomers are vinyl (or bydrocarbyl, e.g. C to Chydrocarbyl, substituted vinyl) esters of C to C carboxylic acids. Thecarboxylic acid is preferably aliphatic, and saturated and preferablymonocarboxylic. Thus, one may use vinyl propionate, vinyl hexoate, vinyloctanoate, vinyl dodecanoate, vinyl behenoate, isopropenyl acetate, oroctadecyl myristoate. The particularly preferred ester is vinyl acetate.The resulting polymer should contain from to 40 weight percent,preferabl 90 to 60 weight percent, of ethylene.

One method of preparing the copolymers involves feeding the monomersinto a tubular reactor which has been previously purged with nitrogen. Asmall amount of oxygen, usually 0.005 to 0.05 wt. percent based on theweight of ethylene is also introduced into the reactor. Alternatively aperoxide initiator, e.g. di-t-butyl peroxide, or a mixture of peroxideinitiator and oxygen may be introduced into the reactor in place ofoxygen alone. A solvent (e.g. benzene, water, saturated hydrocarbons,methanol) may also be employed in the reaction. The pressure ismaintained between 60 and 2700 atmospheres (900 and 40,000 p.s.i.g.),preferably between and 2000 atmospheres (2,000 and 30,000 p.s.i.g.). Thetemperature should be maintained between 40 C. and 300 C., preferablybetween 70 C. and 250 C.

Another method of preparing the copolymers is via a batch process. Sucha process requires a solvent for the reactants, the solvent being forexample toluene or hexane. The preferred solvent however is benzene. Thereaction initiator may be any peroxy compound, preferably di-tbutylperoxide. The temperature of the polymerisation reaction is dependentupon the particular peroxide initiator employed and should be highenough for suflicient decomposition of the initiator to occur. Thistemperature will usually be between 40 C. and 300 C.

For the preferred initiator, i.e. di-tert-butyl peroxide, the mostsuitable temperature is between 130 C. and C. The pressure should bebetween 60 and 1000 atmospheres (900 and 15,000 p.s.i.g.), andpreferably being between 75 and 470 atmospheres (1100 and 7000p.s.i.g.). The autoclave or similar equipment containing the solvent,initiator and vinyl or hydrocarbyl substituted vinyl ester is purgedwith nitrogen and then with ethylene before charging with a sufficientamount of ethylene to yield the desired pressure when heated to thereaction tempertaure. During the polymerization addition ethylene isadded to maintain the pressure at the desired level. Further amounts ofinitiator and/ or solvent, and/ or vinyl and hydrocarbyl substitutedvinyl ester may also be added during the reaction. On completion of thereaction free solvent and unreacted monomers are removed by stripping orsome other suitable process yielding the desired polymer.

The copolymers useful in the invention preferably have a number averagemolecular weight from 3,000 to 60,000 as measured by Vapour PhaseOsmometry (using a Mechrolab Vapour Phase Osmometer model 301A) and/orMembrane Osmometry (using a Mechrolab 1 Membrane Osmometer model 501).The number average Heehrolab Inc., 1062 Linda Vista Avenue, MountainView, Calif.

J tween 0.005 and 0.5% by weight based on the weight of fuel, shale oil,or crude oil.

The copolymer can also be applied down oil wells to crude oil to inhibitthe formation of paraffin deposits, or to dissolve existing deposits onthe sides of the well casing. The copolymer can also be added to crudeoils or residua above ground to facilitate their movement through pipelines. Thus, for example, the copolymer can be added to any NorthAfrican crude, to lower the pour points so that they can be more readilypumped.

The blending of the above-mentioned copolymers in fuels, crude oilsetc., can be facilitated by first forming copolymer concentrates insuitable hydrocarbon blend stocks. Examples of suitable solvents arethose containing a high proportion of aromatic hydrocarbons, e.g.toluene, xylene, kerosene extract, this extract being the highlyaromatic fraction separated from a crude kerosene by a liquid sulphurdioxide extraction process. Further suitable solvents are slack waxes,which are the waxes obtained without purification or refining fromlubricating oil dewaxing processes. Such suitable slack waxes willusually have melting points between 20 C. and 62 C. and oil contents ofto 50 wt. percent.

A suitable composition of such copolymer/solvent blends is 5 to 50% byweight of copolymer, and 95 to 50% by weight of solvent. Thus, forexample, particularly suitable blends have been found to be a blend ofto 30 e.g. by Weight of an ethylene/vinyl acetate copolymer and 90 to70% e.g. 75% of a slack wax or a kerosene extract. These compositionscan be readily blended into fuels to the required concentrations, e.g.up to 1% by weight, at temperatures of about 40 C. and above.

The copolymers may also be used in the fuels, crude oils, etc. inconjunction with other additives commonly used in fuels, e.g.rust-inhibitors, demulsifying agents, corrosion inhibitors,anti-oxidants or dispersants, or other flow improvers or pourdepressants.

EXAMPLE 1 In this example, two copolymers were used, and added indifferent concentrations to two different fuels.

Copolymer A was a random copolymer of ethylene (67 weight percent andvinyl acetate (33 weight percent) having a number average molecularweight of 13,000 as measured by Vapour Phase Osmometry using chloroformas solvent at 37 C. Copolymer B was a random copolymer of ethylene (82weight percent) and vinyl acetate (18 weight percent) having a numberaverage molecular weight of 12,000 as measured by Vapour Phase Osmometryusing benzene as solvent at 37 C. Both A and B were separately blendedwith a slack wax so that the blends contained 25% by Weight of A and 25%by weight of B respectively. The slack wax had a melting point of 40 C.and contained 29 wt. percent of oil. The copolymer/slack wax blends wereseparately blended into two different residual-containing fuel oils Cand D having the following characteristics. Fuel oil C contained 32% byweight of distillate fraction boiling between 350 and 680 F., and 68% byweight of residuum with a boiling point of 680+ F., and it had akinematic viscosity of 43.2 cs. at 100 F. Fuel oil D had an initialboiling point Copolymer eoneen- Upper pour tration, Flow point, F.point, F.

Weight percent 0 D C D Additive:

None 65 25 20 O. 1 25 -15 25 -15 0. 01 30 10 30 25 0. 05 20 10 20 30 O.01 30 5 5 20 EXAMPLE 2 A 1 gallon stainless steel magnetically stirredautoclave was charged with 840 ml. of benzene and then purged withnitrogen then with ethylene. The autoclave was then heated to 150 C. andpressurised with ethylene to 900 p.s.i.g. 220 g. of vinyl acetate wasthen introduced via a metering pump over a period of 2 hours.Concurrently a solution of 22 g. of di-tert butyl peroxide in 66 g. ofbenzene was introduced to the reactor over a period of 3 hours. Thetemperature was maintained at 150 C. and the pressure at 900 p.s.i.g.during the reaction. After the addition of the peroxide was completedthe reaction mass was maintained at 150 C. and 900 p.s.i.g. for anadditional 30 minutes. On completion of the reaction the mixture wascooled and the pressure released. Free solvent and unreacted monomerswere removed by stripping to give copolymer E.

EXAMPLE 3 Following the procedure given in Example 2, the followingcopolymers were made using the charges and reaction conditions given inTable I:

TABLE I Polymer preparation G H I J K L Reaction pressure,

p.s.i.g 1, 350 2, 000 3,000 3, 000 4, 000 3,000 Reaction temperature,

150 150 150 135 150 85 Initial charges:

Benzene, ml l, 000 800 800 800 800 800 Vinyl acetate, ml. 80 80 80 S0Feed rates, ml.,hr

Vinyl acetate 170 140 210 250 Over total time,

hours 1% 2 1% 1% 1% 1% Initiator di-tert butyl peroxide Initiator, n11 l50 l 20 2 20 2 20 Z 20 3 120 Over total time,

hours 1% 2% 1% 1 5 1% 1 Soak time, hours Polymers H I K L l Lauroylperoxide. 2 23 wt. di-tert butyl peroxide in benzene. 3 13.8 wt. lauroylperoxide in benzene.

The polymers prepared in Examples 2 and 3 have the following properties:

POLYMER PROPERTIES 1 Number average molecular Weight measured in toluenesolution at 37 C. using a Mechrolab Vapour Phase Osmometer, Model 301A.

2 Weight/volume percent solution in toluene at 100 F.

3 0.02 weight percent of copolymer in fuel oil C as defined in ExampleI.

4 25 Weight percent copolymer concentrates in toluene were firstprepared and these concentrates were used for preparing the fuel oilblends.

b Intrinsic viscosity of 0.17, toluene at 50 C.

EXAMPLE 4 Copolymers I, K and L from Example 3 were blended intoresiduum M. This residuum has an initial boiling point of 647 F. atatmospheric pressure and a viscosity at 122 F. of 121 Saybolt Furolseconds.

COPOLYMERS IN FUEL M Upper Weight, pour Copolymer 1 percent point None105 0. 1 90 1 25 weight percent additive concentrates in toluene wereused as in Example 3.

EXAMPLE 5 A 25 wt. percent concentrate of copolymer B in a slack wax (asdescribed in Example I) was blended into three crude oils giving thefollowing results.

Upper Upper pour pour Crude oil point point 1 N 70 60 l 25 -5 Q 0 -15residua from the distillation of crude or shale oil, and

about .001 to 10 wt. percent of a pour depressing copolymer of ethyleneand an ester selected from the group consisting of vinyl esters and C toC hydrocarbyl substituted vinyl esters, of C to C saturated aliphaticmonocarboxylic acids, said copolymer having a number average molecularweight in the range of about 4,000 to 60,000 and containing about to wt.percent ethylene.

2. A composition according to claim 1, wherein said oil is crude oil andsaid ester is a vinyl ester.

3. A composition according to claim 2, wherein said molecular weight isin the range of 4,000 to 20,000.

4. A composition according to claim 3, wherein said ester is vinylacetate.

5. A composition according to claim 1, wherein said oil is fuel oilhaving at least 60 wt. percent boiling above 500 F. at atmosphericpressure and having a viscosity between 15 and 3,500 cs. at F., and saidester is vinyl ester.

6. A composition according to claim 5, wherein said molecular weight isin the range of 4,000 to 20,000.

7. A composition according to claim 6, wherein said ester is vinylacetate and said molecular weight is above 5,000.

References Cited UNITED STATES PATENTS 3,048,479 8/ 1959 Ilnyckyj et al.44--62 3,093,623 6/1963 Ilnyckyj 44-62 3,126,364 3/1964 Ilnyckyj 44623,192,165 6/1965 Fields et a1. 44-62 3,254,063 5/1966 Il-nyckyj 44623,236,612 2/1966 Ilnyckyj 4462 3,262,873 7/1966 Tiedje et a1 208-333,393,144 7/1968 Button et a1. 208-33 PATRICK P. GARVIN, PrimaryExaminer Y. H. SMITH, Assistant Examiner US. Cl. X.R. 4462

